Field of the Invention
Embodiments of the present invention generally relate to a system and method for sensing an input object's position over a sensing region of a proximity sensing device.
Description of the Related Art
Input devices including proximity sensor devices, also commonly called touchpads or touch sensor devices, are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems, such as opaque touchpads integrated in, or peripheral to, notebook or desktop computers. Proximity sensor devices are also often used in smaller computing systems, such as touch screens integrated in cellular phones.
Proximity sensor devices are typically used in combination with other supporting components, such as display or input devices found in the electronic or computing system. In some configurations, the proximity sensor devices are coupled to these supporting components to provide a desired combined function or to provide a desirable complete device package. Many commercially available proximity sensor devices utilize one or more electrical techniques to determine the presence, location and/or motion of an input object, such as a capacitive or a resistive sensing technique. Typically, the proximity sensor devices utilize an array of sensor electrodes to detect the presence, location and/or motion of an input object. Due to the often large number of sensor electrodes used to sense the presence and position of an input object with desirable accuracy, and also the need to connect each of these sensor electrodes to the various signal generation and data collection components in the electronic or computing system, the cost associated with forming these interconnections, the reliability of the system and the overall size of the of the proximity sensor device are often undesirably large. It is a common goal in the consumer and industrial electronics industries to reduce the cost and/or size of the electrical components in the formed electronic device. One will note that the cost and size limitations placed on the proximity sensor device are often created by the number of traces that are required, the number of required connection points, the connection component's complexity (e.g., number of pins on a connector) and the complexity of the flexible components used to interconnect the sensor electrodes to the control system.
Moreover, the greater the length of the traces used to interconnect the sensor electrodes to the computer system, the more susceptible the proximity sensor device is to interference, such as electromagnetic interference (EMI), commonly generated by the other supporting components. The interference provided by these supporting components will adversely affect the reliability and accuracy of the data collected by the proximity sensing device. Current commercial electronic or computing systems have commonly resorted to finding ways to minimize the magnitude of the interference by distancing the EMI generating components from the proximity sensing device, adding shielding components to the device package, and/or altering the display processing method, thus making the system more expensive and/or needlessly increasing the size of the complete system package.
Therefore, there is a need for an apparatus and method of forming a proximity sensing device that is inexpensive, reliable and can be integrated within a desirably sized electronic system.